1. Field of the Invention
This invention relates to a method of matching a wheel valve identifier with an identifier of that wheel registered in the memory of an onboard computer of a motor vehicle.
2. Discussion of the Background
According to one method of matching, a valve of the type capable of emitting a field of radio signals, or radio field, is used, containing at least the valve identifier and a state specifying the emitting conditions of the valve. In response to a specific excitation, a specific radio field containing at least one valve identifier and one specific state is emitted by that type of valve. Different information like the tire pressure of the wheel bearing the valve can be included in that field.
The onboard computer possesses in memory the identifiers of the wheels capable of bearing valves of the aforesaid type.
An onboard receiver, combined with the onboard computer, receives the fields emitted by the valves of the vehicles, and even by valves of other vehicles. It transmits them to the onboard computer, which decodes them.
In order to supply data usable by a driver of the vehicle, the onboard computer must allocate the information contained in those fields to the wheels bearing the valves which have emitted them. It must therefore have in memory a table specifying the match between the identifier of each valve and the identifier of the wheel bearing it.
After a wheel change or the first mounting of the wheels, an operator must update that matching table. That update proceeds according to the following stages:    specific excitation of a valve whose operator wishes to match the identifier with the identifier of the wheel bearing it, in order to produce the emission by that valve of a field which is distinguished by a specific state,    reception of the specific field emitted in response to the excitation,    decoding of the specific field,    analysis of at least the “valve identifier” and “state” data contained in the specific field and recognition of the identifier of that valve,    presentation to an operator of at least the “valve identifier” data contained in that specific field, a means of distinction rendering said data distinguishable,    matching of the wheel identifier with the valve identifier by the operator,    input in said memory of the valve identifier matching the wheel identifier.
The prior art also teaches a method in which an operator uses a multifunction tool serving at the same time as specific excitation emitter, receiver of fields emitted by valves, field decoding tool and display tool.
A diagnostic tool, generally available to operate different controls on a vehicle, can serve as interface between the operator and the onboard computer.
More specifically, by means of that multifunction tool, the operator emits a specific excitation, at 125 KHz, for example, to a valve whose identifier is unknown to him. The multifunction tool receives in response a field containing a specific state and emitted on a given frequency, 433 MHz, for example, by the valve excited. It decodes same, retrieves and displays at least the identifier of the emitting valve matching its specific state. That specific state signifies that the field comes from a valve excited by means of the multifunction tool and thus distinguishes it from other fields received by the multifunction tool.
A complex multifunction tool is expensive.
Furthermore, it is usable only with valves emitting on a single frequency, 433 Mhz, for example. Now, not all valves of the type mentioned emit on the same frequency, notably in order to take into account authorizations peculiar to certain countries.
Multifunction tools similar to the one described above, but capable of receiving other frequencies, must therefore be used in order to be able to change wheels equipped with valves of the type mentioned emitting on different frequencies. In the present state of the art, garages have to be equipped with as many different tools as there are emitting frequencies used by those valves.